The double blind clinical trial of human leukocyte interferon has just begun to test its efficacy in preventing recurrences of ocular herpes simplex. It is expected that it will take 12 years in order to obtain statistically valid results. Another double-blind study is in progress testing I.V. Ara-A in patients with deep stromal disease and iritis caused by herpesvirus. New ways of treating ocular herpes simplex will be tested--for example bromodeoxycytidine and tetrahydrouridine, interferons produced in tissue cultures--and their effects on immune response will be studied.